Liebert 50 & 60Hz - Manual (Page 25)

Site Preparation and Installation
17
2.4.4 Electrical Connections, Evaporator or Chilled-Water Unit
Each unit is shipped from the factory with internal wiring completed. Refer to electrical sche-
matic, Figure 11, Figure 25, and Figure 26 when making connections. Electrical connections
to be made at the installation site are:
• Power supply to each ceiling unit and control wiring between the evaporator unit and the con-
densing unit, if applicable.
• Control wiring between the control panel (wallbox) and the evaporator or chilled-water unit
control board.
Power Connections
All power and control wiring and ground connections must be in accordance with the National
Electrical Code (NEC) and local codes. Refer to Unit serial tag data for electrical requirements.
Voltage supplied must agree with the voltage specified on the unit serial tag. A field supplied dis-
connect switch may be required. Consult local code.
Route the electrical service conduit through the hole provided in the cabinet and terminate it at
the electric box. Make connections at the factory terminal block or disconnect switch, L1, L2, L3.
Connect earth ground to lug provided. See transformer label for primary tap connections.
Installer will need to change transformer primary taps if applied unit voltage is other than pre-
wired tap voltage.
An optional single point power kit is available for units that are close coupled (refer to Figure 11
and 2.4.3 - Piping Connections and Coolant Requirements). This kit should be mounted
inside the evaporator unit before installing the unit in the ceiling. Specific installation instruc-
tions are included with the single point power kit.
Control Connections (10-wire on air-cooled, 8-wire on water/glycol cooled)
A field-supplied control connection (24 VAC) is required between the evaporator and the condens-
ing unit. Control wiring must be installed in accordance with the National Electrical Code (NEC)
Class 2 circuit. Glycol-cooled units also require a two-wire control connection to the drycooler and
pump.
Control wiring between the evaporator and the condensing unit must not allow a voltage drop in
the line of more than 1 volt (16 gauge minimum for 75 feet). Do not connect additional electri-
cal devices to the control circuit. The internal control transformer is only sized for factory-
supplied components.
Additional control wiring will be required if your system includes other optional monitoring and
control devices.
Four (4) wire (thermostat type) must be connected between the evaporator control board and the
wall box. See Figure 25 and Figure 26 and see Figure 11 for electrical connections.
!
WARNING
Unit contains hazardous electrical voltage. Disconnect power supply before working
within. Line side of factory disconnect remains energized when disconnect is off.
!
WARNING
UNIT CONTAINS HAZARDOUS ELECTRICAL VOLTAGE. More than one disconnect
may be required to remove power. Evaporator and condensing units may have separate
disconnects. Open all disconnects before working within.
!
CAUTION
Use copper wiring only. Make sure that all connections are tight.